The fugitive who has eluded the authorities in Pennsylvania for nearly two weeks after breaking out of jail is now armed, having stolen a rifle from a house, officials said on Tuesday.

Law enforcement officers, who are now focusing their search on an area about 30 miles north of the jail, responded to a reported sighting of Danelo Cavalcante, 34, around 8 p.m. Monday, Lt. Col George Bivens of the Pennsylvania State Police said at a news briefing Tuesday morning.

Seeing the tracks of his prison-issued shoes at the scene of the sighting, officers followed the trail into the woods. At some point Mr. Cavalcante stole a pair of work boots from a porch and ditched the shoes, which were later found by the police.

A little after 10 p.m., Colonel Bivens said, Mr. Cavalcante saw a garage door that was open. He went inside the garage, where he found a .22 caliber rifle leaning in a corner. The owner of the house was in the garage at the time, and fired several shots at Mr. Cavalcante with a pistol, but Mr. Cavalcante escaped with the rifle.

That Mr. Cavalcante — who has been convicted of murder in Pennsylvania and is wanted in connection with a killing in Brazil — is now armed raises the tensions and the risks in the small communities west of Philadelphia where the manhunt has unfolded in the 13 days since he escaped.

“We consider him desperate, we consider him dangerous,” Colonel Bivens said.

“He’s killed two people previously,” he added. “I would suspect that he’s desperate enough to use that weapon.”

Mr. Cavalcante clambered a wall and escaped from Chester County Prison on Aug. 31, several days after he was sentenced to life in prison for murdering his ex-girlfriend in 2021. He has eluded a legion of law enforcement officers — the number is now approaching 500, Colonel Bivens said — in the quiet, wooded suburbs of Chester County.

Alerts sent to local residents warned them to stay inside, lock their doors and windows, and secure their vehicles, and asked them to review their surveillance camera footage. Late on Monday, officials advised schools in the area to close for the day.

After more than a week hiding out in an area south of the prison, Mr. Cavalcante slipped through a perimeter set by law enforcement and stole a delivery van over the weekend. On Saturday night, he was seen on a doorbell camera miles away. He then apparently drove west, and abandoned the van behind a barn in a small village in northern Chester County after the van ran out of gas.

The confrontation and chase on Monday night took place not far from where the van was found. Officials believe that Mr. Cavalcante is still somewhere in an area of 8 to 10 square miles that is thick with woods.

State and federal authorities, including the U.S. Marshals Service, reward for information leading to the fugitive’s capture. The reward started at $10,000, then was raised to $20,000 and, on Monday, to $25,000.